Interlock switch



.Nov. 11, 1941. -R. K. GA LLUP 2,261,989

INTER-LOCK SWITCH Filed April 27, 1940- INVENTOR, ROYAL y/MLUP 7kg wv-M A TTORNEY.

Patented Nov. 11, 1941 INTERLOCK SWITCH Royal K. Gallup, Rocky Point,'N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application April 27, 1940, Serial No. 331,920

6 Claims.

This invention relates to a new and useful interlock switch which is especially adapted to be attached to the door of a radio transmitter or other high voltage apparatus to disconnect the high voltage circuits when the door is opened for inspection or check-up of the apparatus contained therein.

An object of this invention is to provide a door interlock which is positive in operation and provides the maximum of protection to the operator, yet is simple in its construction and operation. A feature of this invention is the provision of a fixed member having two contacts connected to a circuit to be controlled and a movable member which is arranged to slide and complete the circuit across the two contacts.

Another. feature of this invention is the provision of a movable shield to protect the live circuit contacts.

Door interlock switches, although old in the prior art, have been a notorious source of annoyance and trouble. The interlock switch of this invention has the advantage that it achieves its circuit closing purpose simply and yet for all its simplicity gives a positive operation and the maximum of protection.

This invention will best be understood by referring to the accompanying drawing, in which:

Fig. 1 is a section of the switch of this invention;

Fig. 2 is a front elevation of a door and fixed support to which the interlock switch of this invention is attached; and

Fig. 3 is a section showing the switch of this invention in the open position.

Referring now in detail to the drawing, the fixed portion I, which may be that of a radio transmitter enclosure or any other device which the switch is to be mounted upon, is provided with a plurality of hinges 2 and 3 for hinging a movable element 4 or door of a radio transmitter. Mounted upon fixed member I is a block of insulation material 5 which is shaped substantially that of a quadrant in its cross-section. Door 4 is provided with a slot 6 in which a block of insulation I is arranged and is secured to be slidably supported by means of a threaded pin or operating knob 8. Insulating block 5 is provided with two apertures 9 and ID, in which are arranged two live spring contacts II and I2. Terminal leads l3 and I4 connect to the apparatus which is to be controlled by the switch. A U-shaped conducting member I5 is secured to insulating block 'I and is arranged to complete the circuit between contacts II and I2 when the door is closed and block I is slid in through the apertures 9 and I0. Covering the contact block 5 is a semi-circular collar or shield I6 which is attached to the door by means of screws I! and rotates with the door as it is opened or closed. Collar or shield I6 has two apertures I8 and I9 which are arranged to be in line with spring contacts I I and I2 when the door is closed. Sliding member I5 may then be inserted, thereby completing the interlock switch circuit. The unsupported end of collar I6 rests in a slot 20. In the closed position, it is impossible to open the door since member I5 inserted in block 5 prevents it, thereby providing one form of protection. To open the door, it is necessary to slide member 8 completely out of apertures I8 and I9 which opens the circuit by being disconnected from live contact members II and I2. When the door 4 opens, the collar I6 rotates with it and covers the contact block apertures 9 and Ill, thereby making it impossible to close the circuit by inserting any metallic object between the live terminals I3 and I 4 when the door is opened, thus giving a second form of protection.

Although only one form of this invention is shown, it is to be distinctly understood that it is not to be limited precisely thereto. For example, the sliding block I may be operated by an indicating knob on the front of the door or knob 8 may be operated through a pair of levers by the usual form of door handle.

What is claimed is:

1. An electrical switch interlock comprising a fixed member, a movable member, an insulating member secured to said fixed member, two live fixed contact members of an electrical circuit secured to said insulating member, a movable shield secured to said movable member and having a plurality of apertures therein, a slidable metallic member arranged on said movable member, and means to move a portion of said slidable member through the apertures of said shield to complete said electrical circuit by making contact to said fixed contact members.

2. An electrical switch comprising a fixed member, a movable member, a hinge securing said movable member to said fixed member, an insulating member secured to said fixed member, two fixed contact members of an electrical circuit secured to said insulating member, a movable shield secured to said movable member and having a plurality of apertures therein, a slidable member having a U-shaped conductor arranged on said movable member, and means to move said slidable member through the apertures in said movable shield to complete said electrical circuit by making contact to said fixed contact members.

3. An electrical switch comprising a fixed member, a movable member, a hinge securing said movable member to said fixed member, an insulating quadrant shaped block secured to said fixed member, two fixed contact members of an electrical circuit secured to said insulating block, a semi-circular movable shield having a plurality of apertures therein, a slidable member arranged on said movable member, and means to move said slidable member through the apertures in said movable shield to complete said electrical circuit by making contact to said fixed contact members.

4. An electrical interlock switch comprising a fixed member, a movable member, a quadrant shaped block secured to said fixed member, two fixed contact members of an electrical circuit secured to an insulating member, a semi-circular movable shield secured to said movable member, having a plurality of apertures therein, a slidable member arranged on said movable member, and means to move a portion of said slidable member through the apertures in said shield to complete said electrical circuit by making contact to said fixed contact members.

5. An electrical interlock switch for controlling the circuit of a radio transmitter comprising a fixed member for enclosing radio apparatus, a door having a slot hinged to said fixed member, an insulating block secured to said fixed member, two fixed contact members of an electrical circuit secured within said insulating block, a movable insulating shield secured to said movable member and having a plurality of apertures therein, a slidable member arranged to slide in the slot of said door, and means to move said slidable member through the apertures in said movable shield to complete an electrical circuit of said radio transmitter by making contact to said fixed contact members,

6. An electrical interlock switch for controlling the circuit of a radio transmitter comprising a fixed member for enclosing radio apparatus, a door having a slot hinged to said fixed member, an insulating block secured to said fixed member, two fixed contact members of an electrical circuit secured within said insulating block, a movable shield secured to said movable ROYAL K. GALLUP. 

